Elastic fabric and process for preparing same



Feb. 16, 1965 A. N. ALElxo ETAL. 3,169,558

ELSTIC FABRIC AND PROCESS FOR PREPARING SAME Filed Sept. 13, 1962 MME/V 73 FEED M5775 L17/Vm United States Patent O 3,169,558 ELASTIC FABRIC AND PROCESS FOR PREPARIN G SAME Antonio N. Aleixo, New Castle, and Nicholas C.

Ganoudis, Wilmington, Del., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Sept. 13, 1962, Ser. No. 224,277 6 Claims. (Cl. 139-421) This invention relates to woven elastic fabrics. More particularly, it relates to woven elastic fabrics which contain continuous filaments. of bare spandex in one fabric direction and to a method for the manufacture of such fabrics.

In the past, the elastic yarns generally used in preparing woven fabrics have been rubber filaments covered with inelastic fibers, except where a non-slip surface is desired in the finished fabric. Although covering of the rubber filaments has certain advantages, the covering adds considerably to the bulk of the fabric and increases the cost of the fabric substantially.

More recently, spandex filaments have become cornmercially available as a replacement for conventional rubber yarn, and these too may be used with a covering of inelastic fibers in the weaving of elastic fabrics. However, o'ne of the advantages of spandex filaments is their availability in low deniers, which makes the bare filaments especially desirable for use in fabrics when sheerness is an important characteristic. Incorporation of bare spandex filaments in fabrics is frequently accompanied, unfortunately, by the appearance of unsightly streaks and puckers or the appearance of pin holes, which impair the attractiveness of the fabrics. This is particularly true in fabric construction in which filter either the-warp or the weft filaments are exclusively bare spandex filaments.

It is an object of this invention to provide attractive, woven, elastic fabrics which contain bare spandex filaments as the principal fiber in one fabric direction. Another object of this invention is to provide a process for preparing such fabrics.

With these and other objects in view, the woven elastic fabric of the present invention is comprised of relatively inelastic yarns in one fabric direction and bare, synthetic elastic filaments in the other fabric direction. The bare elastic filaments, which must have a breaking elongation of at least 400%, are woven into the fabric after being twisted to provide a twist multiplier in the range from about 1.25 to about 2.5 at a residual elongation between about 40% and 75%. yBy controlling the twist of the bare elastic filaments, a uniform weave pattern is provided. The process for providing the woven fabric includes the steps of stretching the bare elastic filament and twisting it while under tension to provide the controlled amount of twist. The controlled twist is maintained as the elastic filament is suitably packaged and subsequently fed under controlled tension to a loom where it is interlaced with the inelastic yarn to provide the woven fabric.

In the drawings:

FIGURE 1 is a flow sheet diagraming the process for preparing the fabric of the present invention; andy FIGURE 2 is an enlarged representation of one formv of the woven fabric of this invention.

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2 Referring nowv to the drawings, the fabrics of the present invention may be prepared using known apparatus. In FIG. 1, the elastic filament may be stretched between a pair of rolls and twisted, using a conventional 'uptwister or downtwister, and then forwarded in the twisted condition to a suitable package, such as a bobbin or a warp beam, depending7 on the particular woven fabric construction to be prepared. if the elastic filament is to be used as the weft thread, it may be transferred from a bobbin to a quill in the conventional manner. The quill is then placed in the shuttle of the loom for the weaving operation. The inelastic yarn may be fed from a warp beam to the loom for interlacing with the elastic filament.

The fabric shown in FIG. 2 is a leno fabric in which the elastic filaments 1 appear as the weft thread. The elasticvfilaments are L1Z0-.denier spandex filaments having a twist multiplier within the previously recited critical range. The warp yarn 2 is a relatively inelastic polyester yarn.

The term spandex filament is used in its generic sense to mean a manufactured filament in which at least of the fiber-forming substance is a long-chain, synthetic, segmented polyurethane. Generally speaking, the segmented polyurethanes are prepared from hydroxylterminated prepolymers such as hydroxyl-terminated polyethers and polyesters of low molecular weight. Reaction of the prepolymer with a molar excess of organic diisocyanate, preferably an aromatic diisocyanate, produces an isocyanate-terminated polymeric intermediate which may then be chain extended with a difunctional active hydrogen-containing compound such as water, hydrazine, organic diamines, glycols, amino alcohols, etc. Among the segmented polyurethanes of the spandex type are those described in several patents among which are U.S. Patents, 2,929,801, 2,929,802, 2,929,803, 2,929,804, 2,953,839, 2,957,852, 2,962,470, 2,999,839, and 3,009,901. Many of such polyurethanes, when in filament form, have elongations greater than 400% at .the break. This invention is particularly effective' when applied to the spandex fibers derived from hydrazine and described in U.S. 2,957,852 and dry spunto form a coalesced multifilament yarn as described in U.S. 2,999,839. This category of spandexis accordingly preferred in. the practice of the invention. By bare spandex is meant a spandex filament having no covering of other fibers wrapped or twisted thereabout.

The term` twist multiplier, as used herein, is a factor which relates the twist in turns per inch (t.p.i.) to the cotton count of the yarn. In cotton spinning systems, the formula used is: v

t.p.i.=twist multiplier X \/cotton count I Unless otherwise specified herein, the terms denier and twist multiplier refer to the bare spandex filament at a I twisting draft which provides a residual elongation be- 3 tween about 40% and 75%. By the term draft it is meant the following:

(stretched length) (elongation) relaxed length T 100 Residual elongation is defined as follows:

Draft= 1 Percent residual elongation= other treatments of the extended fabric are not necessary to improve fabric appearance. The fabric need only be stretched slightly during drying.

The following table shows the results obtained when spandex filaments containing varying amounts of twist are woven into a standard leno fabric construction. In the fabrics described, the spandex filaments used were prepared from polymer described in U.S. 2,957,852 and spun into filaments using a dry spinning operation according to U.S. 2,999,839. In preparing the fabric samples, the spandex filaments were used in the weft. The warp yarns in all samples were 1GO-denier polyester yarns having a twist of twenty-one turns per inch. After weaving, the samples were visually examined and subjectively rated as acceptable or unacceptable on the basis of absence or presence of streaks, puckering, and pinholes.

Table Spandex Filaments at Twisting Fin- Fabric Draft Loom Reed Finished Weight Stretch Appcrance of Count Width ished Width (oz./ (Per- Fabric (im) Count (in.) yd!) cent) Nominal Turns Twist (Wett) Relaxed Per Denier Multi- Denier Inch plier (i x 36...- 45 184 X 42 16. 8 4.60 233 420 0 100 0 Unacceptable. 60 X 36. 45 192 x 44 14. 5 4. 12 210 420 10. 7 106 1. 50 Acceptable. 60 x 36. 420 22. 5 98.2 3.05 Unacceptable. 60 x 44- 280 0 60 0 D0. 60 x 44 280 4. 75 66 0.52 Do. 60 X 44-..- 47 165 x 49 17. 5 3. 22 230 280 12. 3 65 1. 34 Acceptable. 60 x 44 47 160 x 58 18.0 3.26 166 280 20.5 55.6 2.07 Do. 60 x 44...- 47 280 33. 4 63. 7 3. 65 Unacceptable.

or 7. If this filament is -twisted at 300% the twisting draft is 4. The percent residual elongation is 1f the filament is twisted at 400% elongation, the percent residual.elongation is or Similarly, if filaments having 400% breaking elongation are twisted at an elongation of 200%, the residual elongation is The type of yarn used with the spandex in the weaving of the fabric will generally be governed by the desired characteristics of the type of fabric to be prepared. Synthetic and natural yarns, e.g., cotton, wool, rayon, nylon, acrylic fiber, polyester fiber, etc., may be used in staple, textured, or continuous filament form to produce a desired effect in the finished fabric. The amount of compression in the finished fabric may be readily controlled by those skilled in the art. The inelastic yarns will generally be twisted to some degree; however, continuous filaments having little if any twist may be used with the elastic filaments of controlled twist.

In accordance with the present invention, it has been found that the elastic filaments must have twist multiplier levels within the range from about 1.25 to about 2.50. At twist multiplier levels below about 1.25, the resultant fabric displays pin holes and streaks, and presents an undesirable appearance. On the other hand, attwist multipliers above about 2.50, the resultant fabric is unacceptable because of a pronounced tendency to curl and pucker. The best appearance is obtained with twist multipliers in the range from 1.35 to 2.10, and these are preferred. At the aforementioned twist multipliers, heat-setting and It will be noted that the acceptable fabrics each have elongations in the weft direction in excess of While in each of the fabric samples described, the elastic filaments have been woven in the weft direction, equally acceptable warp stretch fabrics can be prepared by utilizing the elastic filaments in the warp and the inelastic yarns in the weft. In addition, effect threads may be included in the warp or weft for decorative purposes.

The practice of this invention eliminates streaks and puckers normally encountered with the use of bare spandex in woven elastic fabrics. A further unexpected advantage in the fabrics of this invention is that they are very pleasant to the touch and lack the undesirable rubbery feel of a fabric made with untwisted bare spandex.

The fabrics of this invention are useful in bathing suits, foundation fabrics, universal fitting apparel, formfitting upholstery, slip covers, and surgical bandages.

As many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not to be limited to the specific embodiments thereof except as defined in the appended claims.

We claim:

1. A woven fabric comprised of relatively inelastic `yarns in one fabric direction and bare spandex filaments in the other fabric direction, said spandex filaments having a breaking elongation of at least 400% and a twist multiplier in the range from about 1.25 to about 2.50 at a residual elongation between about 40% and 75%.

2. The fabric of claim 1 wherein said spandex filaments have a twist multiplier in the range from about 1.35 to about 2.10.

3. A woven fabric having a leno construction cornprised of relatively inelastic yarns in the Warp direction and bare spandex filaments in the weft direction, said spandex filaments having a breaking elongation of at least 400% and a twist multiplier in the range from about 1.25 to about 2.50 at a residual elongation between about 40% and 75 4. A process for preparing a high-stretch woven fabric having a uniform weave pattern comprising the steps of stretching a bare spandex filament, twisting said spandex filament while under tension an amount sufficient to provide a twist multiplier in the range from about 1.25

to about 2.50 at a residual elongation between about 40% References Cited in the le of this patent and 75%, and thereafter forming sald woven fabncby UNITED STATES PATENTS weaving sald spandex lam-ent under controlled tension into one fabric direction and relatively inelastic yarn into 3461673 Mlfchell Allg. 3, 1886 the other fabric direction. 5 2,256=l50 Mallory Sept. 15, 1941 6. The process of claim 4 wherein said spandex la- OTHER REFERENCES ment is woven in the weft direction and said inelastic 10 Modem Textile Magazine, July 1962, pages 20 and 51. yarn is woven in the warp direction. 

1. A WOVEN FABRIC COMPRISED OF RELATIVELY INELASTIC YARNS IN ONE FABRIC DIRECTION AND BARE SPANDEX FILAMNETS IN THE OTHER FABRIC DIRECTION, SAID SPANDEX FILAMNETS HAVING A BREAKING ELONGATION OF AT LEAST 400% AND A TWIST MULTIPLIER IN THE RANGE FROM ABOUT 1.25 TO ABOUT 2.50 AT A RESIDUAL ELONGATION BETWEEN ABOUT 40% AND 75%. 